Answer:
The three choices are correct where, choice (b) If the atoms are moved farther apart, they experience forces resisting the separation and begin to move toward each other. And for choice (c) If the atoms are pushed closer together, they experience forces resisting the compression and begin to move far away from each other. Choice (a) also correct where a spring exerts forces to bring balls (atoms) closer together and also exerts forces to move balls (atoms) apart.
Answer:
The star-sphere discovered by the Greeks and other ancient civilizations which shows the physical location in space of the nearby stars.
Explanation:
The celestial sphere is an ideal sphere, without defined radius, concentric with the terrestrial globe, in which the stars apparently move. Some ancient civilizations such as the Greeks assumed that the stars were attached to a celestial sphere, which revolves around the earth, while our planet is always immobile.
Answer:
x_total = 0.17m
Explanation:
We can treat this exercise with the kinematics equations, where in the first part it is accelerated and in the second it is a uniform movement.
Let's analyze accelerated motion
The time that lasts is t = 20 10⁻³ s, the initial speed is zero (v₀ = 0), let's find the length that advances
x₁ = v₀ t + ½ a t²
x₁ = ½ a t²
x₁ = ½ 210 (20 10⁻³)²
x₁ = 4.2 10⁻² m
let's find the speed for the end of this movement
v = v₀ + a t
v = 0 + 210 20 10⁻³
v = 4.2 m / s
with this speed we can find the distance that the uniform movement
x₂ = v t2
x₂ = 4.2 30 10⁻³
x₂ = 1.26 10⁻¹ m
x₂ = 0.126m
the total distance traveled is
x_total = x₁ + x₂
x_total = 0.0420 +0.126
x_total = 0.168m
Let's reduce the significant figures to two
x_total = 0.17m
Average Acceleration = (change in speed) / (time for the change)
Change in speed = (ending speed) - (starting speed)
= 15 m/s - 24 m/s = -9 m/s
Acceleration = (-9 m/s) / (12 sec) = - 0.75 m/s² .